The present invention relates to a diagnostic device for use in a colour sorting apparatus.
A colour sorting apparatus is used for automatically separating grains with a colour different from a reference colour from grains to be sorted such as rice grains, wheat, red beans, soy beans, and peanuts. In such colour sorting apparatus, it is necessary to provide a large number of sorting channels because only one grain at a time is subjected to the sorting operation and therefore there are usually provided 20 to 30 sorting channels. A colour sorting apparatus of the kind to which the diagnostic device according to the present invention may be applied and which has a large number of sorting channels is found in, for example, the U.S. Pat. No. 3,738,484. With a colour sorting apparatus of this kind, if there occurs any malfunction even in only one of those sorting channels, this causes unacceptable grains to be mixed in the acceptable grains which have been sorted, thereby seriously deteriorating the sorting performance of the apparatus.